You’re comparing brands of screwdrivers with different shapes of handles, instead of screwdrivers and hammers.
There are no alternatives that are hidden gems, they would have risen to the top. GIMP is it.
I have switched to GIMP many years ago and by now Photoshop is what feels weird. That’s simply a factor of the unknown. If you are not willing to learn a new flow, then I’m pretty sure you will disregard anything that isn’t Photoshop itself.
Perhaps install a VM in VirtualBox and set it to seamless mode.